Providing efficient and intuitive interaction between a computer system and users thereof is essential for delivering an engaging and enjoyable user-experience. Today, most desktop computer systems include a keyboard for allowing a user to manually input information into the computer system, and a mouse for selecting or highlighting items shown on an associated display unit. As computer systems have grown in popularity, however, alternate input and interaction systems have been developed.
For example, touch-based, or touchscreen, computer systems allow a user to physically touch the display unit and have that touch registered as an input at the particular touch location, thereby enabling users to physically interact with objects shown on the display. More recently, manufacturers are experimenting with table-top or horizontal touch displays. When a touch-surface display is oriented horizontally, it is natural for multiple users to surround and interact simultaneously with the display, which can create a challenging environment for effective touch discrimination.